Fleece fabrics are conventionally produced in any one of a variety of ways, of which two examples are fleece knitting and warp yarn stitch bonding. In fleece knitting, fleece produced for example by a card and cross folder or a pneumatic fleece layer is fed to a stitchbonding head equipped with compound needles in a reciprocatory bar. The needles pull out loops of fleece fibres and form quasi-chain stitch seams by pulling each so formed loop through the previously formed loop. This process produces a fabric which has considerably more strength than the original fleece, but which lacks sufficient strength, even after stentering, to be useful as a textile face fabric. Its stability, its pilling properties and its abrasion resistance are not very good. It finds application as an interlining, or it can be further processed for example by thermobonding or by coating with polyvinyl chloride for use as a leather substitute.
Stitch bonding, on the other hand, with warp yarn more readily provides a useful fabric of adequate strength and stability, for use as a face fabric. In this process, the fleece is produced as in fleece knitting and fed to the stitch bonding head where chain, tricot or other stitch seams such as those used in warp knitting are produced by the compound needles from warp yarns which are laid in the open needle hooks when they penetrate through the fabric.
Such fabrics, although possessed of superior properties in some respects when compared to fleece knitted fabrics, still lack many essential qualities for use as regular textile fabrics. Thus while warp yarn stitch bonded fabrics can be made with adequate strength, especially if long (i.e. about 10 cm) fibre is used in the fleece and the fabrics are stentered, the simple chain stitches produced by a single guide bar machine are easily pulled out to form a ladder. This disadvantage can be overcome by using more complicated stitch formations produced by multiple guide bar machines at the expense, however, of productivity. It has also been proposed to lock the warp yarn stitches by loops of fleece fibers (see U K patent specifications NOS. 1 268 630 and 1 316 013 ) and fabrics produced in this way are already an article of commerce. Even these improved fabrics however have certain disadvantages when compared to woven or circular or warp knitted fabrics constructed entirely of yarn.
Since the warp yarn stitches are required to bond the fleece fibre together, and give strength to the structure, the possibilities of deploying the warp yarn stitches to create interesting surface texture or patterning effects are limited. Thus needles might be spaced in groups to create a pattern of lines running lengthways of the fabric, but the spacing between two adjacent seams cannot be too great or fabric strength will be seriously affected. Furthermore, the pilling and abrasion resistance of warp yarn stitchbonded -- as of fleece fabric generally -- are extremely poor. Thus where a standard pilling test ascribed a value of 1 to a fabric with good pilling properties, a value of 2 to a fabric with intermediate pilling resistance and a value of 3 to a badly pilling fabric, it is necessary to extend this range and ascribe a value of 4 to many stitch bonded fabrics, which exhibit pilling to an extent which can more properly be described as matting.